All of their 5-star TrustPilot reviews seem like they are fake at first glance. They also do not have a robust customer support system, which is also a red flag. It doesn’t necessarily prove that they are scamming but it raises some doubts.

TrustPilot has their contact email listed contact@oxapay.com and on Telegram a business development manager is listed with the handle @Sara_opy. You might try contacting them through these methods if you have not done so already, and mention to them that they have an unresolved scam accusation on Bitcointalk. With such a small online presence this is going to show up high on search results. If they care about their reputation at all they will come here to present their side of the story.